The preface of the paper is also called introduction, which is a short paragraph in front of the text. The preface is the preface of the paper, which aims to explain the ins and outs of this study to readers, arouse readers' interest in this paper, and play a role in outlining and guiding reading interest in this paper. Before writing the preface, we must first clarify several basic questions: What do you want to explain through this article? What are the new discoveries and whether they have academic value? After reading the preface, the general reader can clearly know why the author chose this topic for research. Therefore, before writing the preface, we should know as much as possible about the relevant contents, collect the main data of predecessors and others' work, and explain the rationality of this study.

(1), cut to the chase and don't beat around the bush. Avoid long-winded narration of historical origin and research process. (2) Be concise and focused. We shouldn't talk too much about the common sense content familiar to our peers and in textbooks. When it is really necessary to mention other people's research results and basic principles, we only need to mark them in the form of quotations. In the introduction, when putting forward the work and opinions of this paper, we should make the meaning clear and the language concise.

(3) Reviewing the history should be focused, the content should be closely related to the title of the article, and the background should be introduced around the title, which can be summarized in a few words; Don't write out the methods and results and don't discuss them when prompting the methods used; Although the contents of past documents can be quoted appropriately, they should not be listed in detail, and the preface should not be written as the historical development of research; Don't write the preface as a small summary of the literature, and don't repeat the common sense content already in the textbook or known by researchers in this field.

(4) Respect science and seek truth from facts. In the preface, we should properly evaluate the value of the paper, seek truth from facts and use scientific words. For the innovation of this paper, it is best not to use inappropriate self-evaluation such as "This study is the first report in China", "Filling the domestic blank", "High academic value", "This study has not been reported in China" and "This study is at the leading level at home and abroad".

(5) The content of the preface should not be the same as that of the abstract. Pay attention to using polite expressions, such as "a little knowledge", "limited level", "please correct me" and "throwing a brick to attract jade". It is best not to discuss the preface in sections, not to illustrate and list, not to deduce and prove formulas.

(6) The preface should not be too long. Too long will bore readers, too short will be difficult to explain. For a 3 000-5 000-word paper, the number of words in the preface should generally be 200-250.